This invention relates to the field of transfer assemblies which are used to transfer workpieces through a plurality of workstations. More particularly, it relates to transfer assemblies used in progressive die type punch presses.
Workpiece transfer assemblies used in progressive die type punch presses are well known in the prior art. Despite their long history of use, many, if not all, of the prior art transfer assemblies are difficult to adapt to use with different die configurations, because of the complex assemblage of mechanical parts associated therewith.
HMS Products Co. has developed a three-dimensional transfer system (xe2x80x9cTriAxis Transfer Models 4 and 6xe2x80x9d) which comprises features to facilitate adaption to different die geometries. In particular, HMS"" transfer system includes an adjustable cam for varying the distances travelled by associated workpiece engaging means. However, HMS"" transfer system requires two separate motive means to effect all three advancing/returning, clamping/unclamping and lifting/lowering operations. A first motive means, namely the press ram, effects both clamping/unclamping and lifting/lowering, while a second motive means effects only advancing/returning. By requiring two separate motive means, synchronization considerations are introduced. Further, with respect to the clamping/unclamping and lifting/lowering, HMS"" transfer system performs these operations using torque transmitted through cams, levers and rods operatively connected to the press ram. Such assembly of parts introduces manufacturing complexity and additional maintenance considerations. Further, despite other aspects, as were described above, such assembly still introduces difficulties when attempting to adapt HMS"" transfer process to different die configurations.
In order to provide an improved transfer apparatus for simultaneously forming/shaping one or more workpieces at a station and for transferring such workpieces from such station to another station, or to a collecting site, the present invention comprises, in one of its broad aspects, an apparatus for transferring workpieces between successive die stations in a stamping press, including an elongated bar having a plurality of spaced workpiece engaging means for engaging workpieces at successive die stations, comprising motive means. A drive frame member is coupled to the motive means and laterally and longitudinally propelled by the motive means. Cam follower means are provided and propelled by the drive frame member. Cam plate means is coupled to the bar, having a first cam slot means and a second cam slot means. The first cam slot means receives the cam follower means, whereby the cam plate means is propelled both horizontally and vertically by the cam follower means. Cam stop means are disposed in the second cam slot means to prevent the cam plate means from motion in the horizontal direction during motion in the vertical direction and to prevent the cam plate means from motion in the vertical direction during motion in the horizontal direction. Motion transmitting means are coupled to the drive shaft and disposed adjacent to the cam plate means. The motion transmitting means drive the cam plate means longitudinally when propelled by the drive frame member.
According to another aspect of the present invention, an apparatus for transferring workpieces between successive die stations in a stamping press, including an elongated bar having a plurality of spaced apart workpiece engaging means for engaging workpieces at successive die stations is provided, comprising motive means, a drive frame member coupled to the motive means and laterally and longitudinally propelled by the motive means, a first cam follower and a second cam follower, each propelled by the drive frame member, a first cam plate and a second cam plate, each of the cam plates coupled to the bar in spaced apart relationship and having a first cam slot means and a second cam slot means, the first cam slot means of the first cam plate receiving the first cam follower for driving the first cam plate horizontally and vertically with respect to the die stations and the first cam slot means of the second cam plate receiving the second cam follower for driving the second cam plate horizontally and vertically with respect to the die stations, a first cam stop and a second cam stop, the first cam stop disposed in the second cam slot of the first cam plate and the second cam stop disposed in the second slot of the second cam plate, for preventing each of the first cam plate and the second cam plate from motion in the horizontal direction during motion in the vertical direction and for preventing the first cam plate and the second cam plate from motion in the vertical direction during motion in the horizontal direction, and a first motion transmitting plate and a second motion transmitting plate, each coupled to the drive frame member, the first motion transmitting plate disposed adjacent to an inner surface of the first cam plate and the second motion transmitting plate disposed adjacent to an inner surface of the second cam plate, for driving each of the first cam plate and the second cam plate longitudinally when propelled by the drive frame member. More particularly, the first cam slot is vertically inclined. The cam stop can further comprise a cam stop follower which is received by the second cam slot. Also, second cam slot can further include a substantially horizontal first slot portion and a substantially vertical second portion, disposed in substantially orthogonal relationship to each other, and an arcuate portion interconnecting the first and second slot portions. Preferably, the motive means is a tri-axial robot capable of movement in three planes (i.e. three directions). To provide aid in overcoming a portion of the force required to move the cam plate means vertically, assist means can also be provided. Further, in order to provide guided longitudinal movement to the cam stop, an elongated rail can be provided wherein the elongated rail slidably receive the cam stop.
In another aspect, the present invention provides an apparatus for attachment to a robot for transferring workpieces in a multi-station stamping press, including an elongated bar having a plurality of spaced apart workpiece engaging means for engaging workpieces at successive die stations, characterized in that the tool comprises a drive frame member coupled to the robot and propelled by the robot laterally of and parallel to an axis parallel to the bar, a first cam follower and a second cam follower, each propelled by the drive frame member, a first cam plate and a second cam plate, each of the cam plates coupled to the bar in spaced apart relationship and having a first cam slot means and a second cam slot means, the first cam slot means of the first cam plate receiving the first cam follower for driving the first cam plate horizontally and vertically with respect to the die stations and the first cam slot means of the second cam plate receiving the second cam follower for driving the second cam plate horizontally and vertically with respect to the die stations, a first cam stop and a second cam stop, the first cam stop disposed in the second cam slot of the first cam plate and the second cam stop disposed in the second slot of the second cam plate, for preventing each of the first cam plate and the second cam plate from motion in the horizontal direction during motion in the vertical direction and for preventing the first cam plate and the second cam plate from motion in the vertical direction during motion in the horizontal direction, and a first motion transmitting plate and a second motion transmitting plate, each coupled to the drive frame member, the first motion transmitting plate disposed adjacent to an inner surface of the first cam plate and the second motion transmitting plate disposed adjacent to an inner surface of the second cam plate, for driving each of the first cam plate and the second cam plate longitudinally when propelled by the drive frame member.
In yet another aspect, the present invention provides an apparatus for transferring workpieces between successive die stations in a stamping press, including an elongated bar having a plurality of spaced workpiece engaging means for engaging workpieces are successive die stations comprising: a lifter arm having a first arm end and a second arm end, the first arm end pivotally coupled to and propelled by motive means, the second arm end pivotally coupled to said bar, a shaft extending from the lifter arm, a guide slot having a first slot end and a second slot end, wherein the first slot end is vertically disposed above the second slot end, a cam follower connected to the shaft and adapted for travel within the guide slot, wherein such travel causes rotation of the shaft and vertical displacement of the first arm end of the lifter arm. The guide slot can further comprise a substantially horizontal slot segment extending from the first slot end, and an arcuate slot segment terminating at the second slot end and characterized by an upwardly facing concave profile, the arcuate slot segment extending from and communicating with said substantially horizontal slot segment, wherein the vertical displacement of the first arm end of the lifter arm occurs during travel of the cam follower within the arcuate slot segment. The first slot end can be disposed distally from the bar relative to the second slot end. The arcuate slot segment can be characterized by a constant radius of curvature. The apparatus can further comprise a control arm extending from the shaft, wherein the cam follower extends from the control arm, and a guide pin is engaged to the control arm during travel of the cam follower within the arcuate slot segment such that the control arm rotates about a fixed axis as the cam follower travels within the arcuate slot segment. The control arm can include a sidewall providing a horizontally orthogonal surface for continuously engaging guide pin during travel of the cam follower within the arcuate slot segment. The sidewall can be characterized by an arcuate profile having a radius of curvature substantially similar to that of the arcuate slot segment.